Sex means different things to different people and the idea of “having sex” varies from one person to the next. New research out of the Kinsey Institute at Indiana University asked a representative sample of 18- to 96-year-olds what the term meant to them and found that there is no uniform definition.

For instance, oral sex was considered “real sex” to 30 percent of study participants while engaging in penile-anal penetration was defined as sex by 81 percent of contributors. An overwhelming 95 percent defined penile-vaginal intercourse having had sex, but this rate dropped to 89 percent if there was no ejaculation. Significantly fewer men (77 percent) in the oldest age group agreed that penile-vaginal intercourse qualified as sex.

The study asked 486 Indiana residents, "Would you say you 'had sex' with someone if the most intimate behavior you engaged in was ...," followed by 14 behaviorally specific activities.

The results of this study are relevant to more than just “idle gossip”, as definitions of sex can impact medical research, medical treatment and health education.

"Researchers, doctors, parents, sex educators should all be very careful and not assume that their own definition of sex is shared by the person they're talking to, be it a patient, a student, a child or study participant," explains Brandon Hill of the Kinsey Institute. “It is common for a doctor, when seeing a patient with symptoms of sexually transmitted infections, to ask how many sexual partners the patient has or has had. The number will differ according to the patients' definitions of sex.”

"There's a vagueness of what sex is in our culture and media," says co-author William L. Yarber. "If people don't consider certain behaviors sex, they might not think sexual health messages about risk pertain to them. The AIDS epidemic has forced us to be much more specific about behaviors, as far as identifying specific behaviors that put people at risk instead of just sex in general. But there's still room for improvement."

The study is published in February's issue of the international journal Sexual Health.